Method of recording/reproducing digital data and apparatus for same

ABSTRACT

A digital data recording/reproducing method includes the steps of: interleaving data on a PI code for each PI code of a 208-row ECC block; and converting a short burst error into random errors by dispersing errors on the PI codes. Moreover, the digital data recording/reproducing method increases correction capability against several bytes to several tens bytes of errors generated at random without changing burst error correction length by performing this processing for respective PI codes by using interleave rules that are different as much as possible from one another.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.11/931,964, filed Oct. 31, 2007 (now U.S. Pat. No. 7,421,626), which isa continuation of U.S. application Ser. No. 11/025,489 (now U.S. Pat.No. 7,305,606), filed Dec. 28, 2004, which is a continuation of U.S.application Ser. No. 09/931,996 (now abandoned), filed Aug. 17, 2001,which claims priority from Japanese Application No. 2000-371486, filedDec. 1, 2000 and Japanese Application No. 2000-381652, filed Dec. 11,2000, all of which are herein incorporated by reference for allpurposes.

BACKGROUND OF THE INVENTION

The present invention relates to an error correction technology toremove an error, in particular, to a digital data reproducing method, adigital data recording method, and apparatus using error correction byproduct code. In particular, the present invention relates to a datarecording and reproducing method, and an apparatus for performinginterleave in byte unit to the data consisting of multiple lines.

Although the present invention is widely applicable to digital datareproducing systems and recording systems that perform error correctionby product code, it will be described here by citing a DVD datareproducing system and a data recording system as examples.

A DVD (digital versatile disc) is a medium which has about 7 times thecapacity of a CD (compact disc). As a medium that records data on a DVD,there are DVD-RAM, DVD-R, and DVD-RW. Recordable media are becomingincreasingly more popular, as seen in the recent growth of CD-R.

A format of DVD-RAM will be described below. In a present DVD,interleave is performed per row to the data consisting of multiplelines.

First, an overview of demodulation processing of recorded data onDVD-RAM will be shown by using FIG. 3. The main data 310 that has beenrecorded is divided into blocks of 2048 bytes. As shown in FIG. 4, eachblock includes 4 bytes of identification data (ID) 401, 2 bytes of IED(ID Error Detection Code) 402 that is an ID error detecting code parity,and 6 bytes of RSV (reservation bytes) 403 that is a reservation area,in addition to the main data (2048 bytes) for a data stream of 2060bytes. Furthermore, 4 bytes of error detecting code parity (EDC) 404 isadded to the end of a data stream of 2060 bytes. The resulting 2064bytes constitute data unit 1 (before scramble) 304 and is organized intotwelve rows of 172 bytes per row as shown in FIG. 4. Next, according toa scramble rule determined with the value of the ID part of the dataunit 1, scramble processing is performed on the 2048 bytes of the maindata part 310 to produce a data unit 1 (after scramble) 305. Sixteeninstances of these data units (after scramble) 1 are combined to form adata field comprising 192 rows×172 columns bytes, e.g., (see data field306 in FIG. 5. Next, 16 rows of Parity of Outer-code (PO) data are added(step 306) to the 192-row data field to produce a 208-row×172 columndata field. Next, ten bytes of Parity of Inner-code (PI) is added (step307) to each of the 208 rows, extending each row to 182 bytes, to formone ECC block. Then, a PO interleave operation to interleave the sixteenrows of PO data (182 bytes wide) with the original 192-row data field.More specifically, a PO row is added at the end of each instance of dataunit 1 (i.e., twelve rows) in the 192-row data field to form sixteen13-row data units 2 (step 308). After an 8/16 modulation operation isperformed to convert the 8-bit data to 16-bit data, twenty-six SYNCcodes are added, per one data unit 2 to form sixteen data units 3 (step309).

Hereafter, each data unit configuration will be described in detail.

First, 2064 bytes of data are configured as shown in FIG. 4, comprising2048 bytes of main data (310), 4 bytes of identification data (ID401),IED (ID error Detection Code) 402 that is an ID error detecting codeparity, 6 bytes of RSV (reservation bytes) 403 that is a reservationarea, and 4 bytes of EDC (error Detection Code) 404. A data unit (afterscramble) 1 (305) is a data unit in which the 2064 bytes of data areorganized as twelve rows of 172 bytes each, where the 2048 bytes of maindata part are scrambled.

Sixteen data units (after scramble) 1 (306) constitute a 192 rows of 172bytes each in a data field 306 and are configured by combining sixteeninstances of data units 1 (305) as shown in FIG. 5.

An ECC block 307 is a unit of error correction processing in DVD and isa product code (known as a cross Reed Solomon code). The product code isformed as follows. As shown in FIG. 6, an outer-code is configured bydefining sixteen data units 1 as information data and treating each of172 columns as RS (208, 192, 17); thus 16 rows of parity of outer-codePO 502 are added as error correction data. After that, an inner-code isformed by treating the resulting 208 rows as RS (182, 172, 11) in thesame direction as the direction of a main data list and the recordingdirection in a DVD (parity of inner-code PI 501 is added as errorcorrection data). A data unit 2 (308) is a data unit after the formationof the ECC block 307, and is a 13-row×182 byte data unit that isconfigured by interleaving each of the sixteen rows of PO 502 among thedata units as shown in FIG. 7.

A data unit 3 (309) is a data train obtained by adding eight kinds(SY0-SY7) of synchronizing signals 801 (SYNC) at the head of each blockat every 91 bytes of the data unit 2 as shown in FIG. 8. For example,SY0 (SYNC code 0) in the head of the unit, SY1-SY4 cyclically insertedin the head of each row, and SY5, SY6 and SY7 inserted foridentification of each row, and performing 8/16 modulation converting8-bit data into 16-bit data. Moreover, it is possible to identify aposition of data, which is reproduced, in the data unit 3 with thegenerating pattern of SYNC 801 from an addition method of this SYNC 801at the time of reproduction.

After such conversion from the data unit 1 to the data unit 3, datamodulated into a DVD is recorded with NRZI (Non Return to Zero)conversion being performed.

Moreover, the list of main recorded data on the DVD does not changeduring the data format conversion process such as scramble, ECCencoding, and PO interleave. Hence, the list and sequence of recordeddata on the DVD are equal to the list and sequence of main data.

Therefore, the recorded data on DVD is reproduced in a reverse processof data processing performed in FIG. 3.

Hereafter, conventional data processing at the time of DVD reproductionwill be described by using FIG. 9

The 8/16 demodulation is performed while determining a position in thedata unit 3 (902) by using SYNC 801, and the data unit 2 (903) isgenerated. Next, the PO interleave is reversed (deinterleaved) whiledetermining a position of the data unit 2 in an ECC block by using ID401, and an ECC block 901 corresponding to the ECC block 307 beforeerror correction is formed.

The reproduction data from the DVD is susceptible to error from variousfactors. Hence, error correction to a maximum of 5 bytes per inner-code(normally, although each data constituting the code is expressed by“word” or “symbol” in error correction, here, the data is explained byusing “byte” as an example of a data unit) is performed in the errorcorrection to inner-code having the same list as a data list recorded inthe DVD. The correction of an error, included in each outer-code, to amaximum of 16 bytes is performed, and error is removed by outer-codeerror correction. After that, error correction data PI 501 and PO 502are removed from the ECC block 901, 16 data units 1 (305) shown in FIG.5 is obtained.

The data of the data unit 1 (305) de-scrambled (304) and is restoredinto ID, IED, RSV and 2048 bytes of main data (303) again afterperforming the error detection processing by using EDC so as to verifythat erroneous correction is not performed in the error correctionprocessing.

The above is the overview of the data signal processing at the recordingand reproduction of a DVD.

In the error correction processing in the reproduction of a DVD that isdescribed by using FIG. 9, the error correction of a PI having anidentical list with the one of the recorded data in the DVD isperformed.

The relationship of data placement on DVD and data placement on ECCblock is effective in view of making it possible to correct acomparatively long burst error by performing error correction, whichuses a result as error position information in outer-code errorcorrection after not letting errors, continuously arising as shown byblack parts in FIG. 10C, dispersed, and several uncorrectable errorarising in the inner-code error correction. The vanishing correctionmethod is an error correction method of performing the correction bydetermining outer-code error positions using the correction result ofthe inner-code as described in this specification.

Nevertheless, an uncorrectable error arises in plenty of outer-codeswhen short burst errors randomly arising as shown by black parts in FIG.10A pile on in a specific outer-code. Error correction is impossible forthe burst error in the inner-code error correction, and the number oferrors exceeds the number of correctable outer-code. (FIGS. 10B to 10Dwill be described later.)

Moreover, in connection with the increase of high-density recording datafor increasing capacity, one or two bytes of error due to dust andscratches of a current DVD become a short burst error. Thus, the averagelength of time for error correction (byte length) increases, and it isestimated that the case that an uncorrectable error arises willincrease.

As a countermeasure for these errors, there is an invention disclosed inJP-A-8-125548.

The invention disclosed in JP-A-8-125548 is a method of making a bursterror dispersed in the entire product code by rearranging thepredetermined data in the product code every several bytes.Nevertheless, in the product code having a ratio of inner-code toouter-code like a DVD, there is a problem of not being able to securecorrection capability, which is equivalent to a conventional method, fora burst error over ten or more lines. This is because there is a casethat, since the burst error is dispersed in the outer-code direction byperforming the rearrangement between lines, an area of uncorrectableerrors increases. On the other hand, the present invention does not letan error become dispersed in an outer-code direction because the presentinvention does not rearrange the data between lines, and hence it ispossible to maintain the ability to correct for the burst error.

Moreover, this is different from the present invention in that arearrangement range is the entire ECC block and arrangement rules arenot changed every line.

Other countermeasures for these errors are described in JP-A-3-266264and JP-A-9-54956. These inventions are going to raise the tolerance foran burst error by arranging words, included in code words in the columnand row directions, so that the words may be mutually apart equally toor more than predetermined distance.

However, this invention is different from the present invention in thatthis invention does not change arrangement rules every line and performsrearrangement over plural lines, and there is a possibility of not beingable to maintain the burst error length.

SUMMARY OF THE INVENTION

An object of the present invention to provide technology for raisingcorrection capability of a short burst error, which is estimated toincrease in future, while securing the correction capability, which isequivalent to conventional technology, for an burst error over severaltens of lines.

Major means of the present invention for solving an above subject willbe described below.

The present invention is a data recording method of recording data on arecord medium, and is intended to improve error correction capacity byrearranging data in sequence per byte for a data train consisting of twoor more bytes which constitute the error correcting code for recordingdata on this record medium and recording the data on the above-describedrecord medium.

In addition, the present invention is intended to improve the errorcorrection capacity by rearranging data per byte in sequence for partsof a data train except identification information out of the data trainconsisting of two or more bytes which constitute the error correctingcode for recording data on this record medium, and recording the data onthe above-described record medium.

Moreover, the present invention is intended to improve the errorcorrection capacity by generating error correcting code through addingerror correction data to the data for recording on this record medium,rearranging data, forming this data train, per byte about the data trainwhich constitutes this error correcting code, demodulating the datatrain which is rearranged in its sequence for data per byte, andrecording the modulated data train on the above-described record medium.

Further, the present invention is a data reproducing method thatreproduces the data modulated and recorded on the record medium. Thepresent invention is intended to improve the error correction capacityby demodulating the data train recorded on the record medium, restoringthe data train, which is demodulated and rearranged according to thepredetermined rule, to the data train in the sequence before beingrearranged per byte for data forming the data train, correcting theerrors that are included in the error correcting code restored to thedata train in the sequence before being rearranged, and reproducing thedata whose errors are corrected.

Furthermore, the present invention is a data recording apparatusrecording data on a record medium. The present invention is intended toimprove the error correction capacity by the data recording apparatuswhich comprises a circuit generating error correcting code for recordingdata on the record medium, a signal processing circuit which rearrangessequence for data per byte about a data train which consists of two ormore bytes which constitutes the error correcting code, and a modulationcircuit which modulates the data train which are rearranged in itssequence for data per byte.

Still further, the present invention is a data reproducing apparatusthat reproduces data modulated and recorded on a record medium. Thepresent invention is intended to improve error correction capacity by adata reproducing apparatus characterized in comprising a demodulationcircuit which demodulates the data train recorded on the record medium,a signal processing circuit which restores the data which forms a thedata train to the data train in the sequence before being rearranged inthe sequence per byte about the data train that is demodulated by thedemodulation circuit and is rearranged according to a predeterminedrule, an error correcting circuit which corrects the errors included inthe error correcting code restored to the data train before beingrearranged by the signal processing circuit, a reproducing circuit whichreproduces the data which had the error corrected by the errorcorrecting circuit.

Thus, when the byte interleave for each row (here, the row has the samelist as the data list recorded on the record medium) of a product codeis performed under a rule different every row, that is, when datarearrangement is performed according to the rule which is differentevery inner-code of the ECC block 307 in a DVD, several bytes to severaltens bytes of short burst error is dispersed in degree different everyrow. Hence, conventional errors shown in FIG. 10A become errors shown inFIG. 10B. Since an error count is equalized on outer-code in FIG. 10Beven if uncorrectable errors are generated in the outer-code errorcorrection in FIG. 10A, the probability of further decreasing the errorsincluded in data by the outer-code error correction becomes high.

This effect means that it becomes possible to obtain characteristics oferror correction still better than those of a current DVD by performingthe repetitive decoding, which performs the same error correctionrepeatedly again, after performing error correction to inner-code anderror correction to outer-code that are effective to random errors.

Furthermore, if performing interleave processing within each row of theproduct code, it becomes possible to secure the burst correction lengththe same as the former. This is because data dispersion does not occurin the direction of line of data formed by outer-code, even if the errorgenerated like FIG. 10C is set to FIG. 10D by the byte interleave.

Thus, in the present invention, an error count is equalized even at thetime of an uncorrectable error arising conventionally, without changingburst correction length by performing the byte interleave every row of aproduct code under a rule different every row, rearranging the data byusing a rule different every row, and making the data dispersed so thatseveral bytes to several tens bytes of short burst error may have notcorrelation. Hence, the probability that more errors can be correctedbecomes high. Moreover, in many cases, in the repeat correction havingthe excellent capacity to a random error, it also becomes possible tocorrect errors more than those in the past in a repeat count equal to orless than that in the past.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a data processing flow at the time ofrecording when the present invention is applied to a DVD;

FIG. 2 is a diagram showing an example of PI interleave;

FIG. 3 is a block diagram showing a data processing flow at the time ofrecording of the DVD;

FIG. 4 is a diagram showing a data unit 1 after scramble;

FIG. 5 is a diagram showing 16 data units 1 after scramble;

FIG. 6 is a diagram showing an ECC block;

FIG. 7 is a diagram showing 16 data unit 2;

FIG. 8 is a diagram showing a data unit 3;

FIG. 9 is a block diagram showing an example of a data processing flowat the time of reproduction of the DVD;

FIGS. 10A-10D are drawings showing an effect at the time of PIinterleave for a short burst error and a long burst error;

FIG. 11 is a diagram showing one ECC block after PI interleave;

FIG. 12 is a block diagram showing a data processing flow at the time ofreproduction when the present invention is applied to the DVD;

FIG. 13 is a diagram showing an example of processing for canceling PIinterleave (deinterleave);

FIG. 14 is a diagram showing an example of a data unit 2 after PIinterleave;

FIG. 15 is a block diagram showing an example of a DVD recording andreproducing apparatus to which the present invention is applied;

FIGS. 16A and 16B are block diagrams showing examples of M-seriesgenerating circuits;

FIGS. 17A and 17B are block diagrams showing examples of M-seriesgenerating circuits;

FIGS. 18A and 18B are block diagrams showing examples of constitutingeach address generating circuit by using an address decoder;

FIG. 19 is a block diagram showing an example of a PI interleavecircuit;

FIG. 20 is a block diagram showing an example of a PI deinterleavecircuit (circuit which cancels PI interleave);

FIG. 21 is a block diagram showing an example of PI interleave beingperformed for two inner-codes under one PI interleave conversion rule;

FIG. 22 is a block diagram showing an example of PI interleave beingperformed every two bytes to one inner-code;

FIGS. 23A and 23B are block diagrams showing examples of respectiveM-series generating circuits;

FIG. 24 is a block diagram showing an example of an arithmeticprogression generating circuit;

FIG. 25 is a block diagram showing an example of a PI interleavecircuit; and

FIG. 26 is a block diagram showing an example of a PI de-interleavecircuit (circuit which cancels PI interleave).

DESCRIPTION OF THE EMBODIMENTS

Hereafter, the present invention will be described by using drawings.Here, the present invention will be described by making a DVD datareproducing system, and a data recording system be examples.

FIG. 1 shows an example of showing data processing steps at the time ofrecording when the present invention is applied to a current DVD logicalformat shown in FIG. 3.

FIG. 1 will be briefly described. The main recorded data 310 is dividedinto 2048 bytes. In each head, as shown in FIG. 4, 4 bytes ofidentification data (ID) 401, IED (ID error Detection Code) 402 that isID error detecting code parity, and 6 bytes of RSV (reservation bytes)403 that is a reservation area are added. Furthermore, 4 bytes of errordetection code parity (EDC) is added to 2060 bytes of this data stream,then 2064 bytes of data unit (before scramble) 1 (304) is organized intotwelve rows of 172 bytes each. Next, according to a scramble ruledetermined with the value of the ID part of the data unit 1, scrambleprocessing is performed on the 2048 bytes of the main data part toproduce a data unit (after scramble) 1 (305) which is twelve rows×172bytes. Furthermore, sixteen rows of Parity of Outer-code (PO) data isadded to a 192 row×172 byte data field comprising sixteen data units 1(306), to produce a 208-row data field. Next, ten bytes of Parity ofInner-code (PI) is added to each of the 208 rows to form one ECC block(307) which is a 208 row×182 byte cross Reed-Solomon code. Next, in a PIinterleave operation, the data in each row of the ECC block isrearranged on a byte-by-byte basis according to each rule to obtain aninterleaved ECC block 101. Then, a PO interleave operation interleaveseach of the 16 rows of PO (and PI) data among the sixteen data units 1of the original 192 rows in the data field. Then, 8/16 modulation isperformed to convert all data into 16 bits from 8 bits, followed by theincorporation of twenty-six SYNC codes for each data unit 2 to form dataunits 3 (103).

However, although PI interleave is performed immediately after ECC blockgeneration in FIG. 1, naturally, it is no problem to perform PIinterleave after constituting the data unit 2, or after constituting thedata unit 3.

Moreover, the “word” and the “symbol” which are the unit of data arealso described as a “byte” here.

In FIG. 1, the added PI interleave operation is a byte interleaveoperation based on a certain rule for rearranging the sequence of 182bytes of data (inner-code) of each row in the ECC block of DVD as shownin FIG. 2. That is, the added PI interleave operation shows theprocessing for rearranging the byte sequence about the data train whichconsists of a plurality of bytes constituting error correcting code.Here, the data train means an inner-code forming the ECC block, that is,an arrangement of the data in the row direction. At this time, theeffect in the point of dispersion of errors becomes large by usingconversion rules (interleave rules, F_(i)(x)) that have no correlationand are different from one another in the 208 rows of inner-codeincluded in the ECC block. However, it is possible to obtain the effectof error dispersion even if this PI interleave is performed by using atleast two kinds of conversion rules (interleave rules) F₁(x) and F₂(x).Moreover, data Di, 0; Di, 1; Di, 2; . . . ; Di, 181 show the dataconstituting the inner-code in the i-th row of an ECC block, and Di,171; Di, 172; . . . ; Di, 181 correspond to the parity of inner-code PI.Therefore, the data train (B) generated by performing PI interleaveoperation on the data train (A) is not always inner-code.

It is also possible to perform PI interleave, which rearranges therecord sequence of this data, among a plurality of inner-codes. In thiscase, although it becomes possible to obtain still higher correctioncapacity to a random error, burst error length become short.

FIG. 11 is a diagram showing an ECC block (101) after performing the PIinterleave shown in FIG. 1. This shows the status that each row of theECC block shown in FIG. 6 is given PI interleave and is transformed.

FIG. 12 shows a data conversion flow at the time of recording data,generated after performing the data conversion process shown in FIG. 1,on a DVD and reproducing the data.

In FIG. 12, a data unit 2 (1203) is generated from the data that isrecorded on the DVD while determining the position in the data unit 3 byusing SYNC801, and performing 8/16 demodulation. Next, a PO deinterleaveoperation is performed to produce an ECC block (1201) as shown in FIG.11, while determining the position of the data unit 2 in the ECC block307 by using ID401. The PO deinterleave operation is the inverse of theoperation shown in FIG. 1 where the PO row was inserted after everytwelfth row. Then, the ECC block (1201) is restored to an ECC block(901) shown in FIG. 6 by applying the conversion rule G_(i)(y), which isthe inverse transformation of F_(i)(x) and is shown in FIG. 13. Thus,the bytes in each row are reorganized according to the inverse functionG_(i)(y) to restore the symbol train (A) from the symbol train (B).After this, as usual, an error of up to 5 bytes is corrected in eachinner-code by the error correction to inner-code, and an error of up to16 bytes, included in each outer-code, by the error correction toouter-code is corrected (306). Then, ID, IED, RSV, and 2048 bytes ofmain data (303) are obtained again after removing the data PI and PO forerror correction required for error correction processing, restoring theECC block to the 16 data unit 1 (305) shown in FIG. 5, cancelingscramble (304), and performing error detection processing by using EDC.In addition, as for conversion rules F_(i)(x) and G_(i)(y), theapparatus may have the information as rules defined beforehand.Alternatively, the conversion rules F_(i)(x) and G_(i)(y) may berecorded on the medium itself, and the apparatus may read theinformation. In the latter case, it is possible to perform theabove-described processing after reading conversion rules F_(i)(x) andG_(i)(y) first, and to determine the conversion rules F_(i)(x) andG_(i)(y) for every disk unit, ECC block unit, frame unit, or the like inthe apparatus.

However, in the demodulation process shown in FIG. 12, the position inthe ECC block is determined by using the ID. Thus, if a PI interleaveoperation is performed where the interleave function F_(i)(x) varies foreach row, it is not possible to determine x=G_(i)(y) at the time ofrestoring a data train since a conversion rule y=F_(i)(x) for PIinterleave for a row including ID cannot be found. Hence, it becomesvery difficult to seek the ID.

Therefore, the information showing the position in a product code isshown, that is, ID and IED (IED is also required when the reliability ofID is required) are not subjected to any data interleave operation on aDVD. Consequently, rows including this information are subject PIinterleave processing by processing only 176 bytes (e.g., bytes 7through 182) of data and leave the 6 bytes of identification informationsuch as ID and IED unaltered.

When this is applied to a DVD, the data unit 2 (102) shown in FIG. 1becomes as shown in FIG. 14. In this case, identification informationcontaining EDC, RSV, etc. cannot be obtained until the code is decodedinto the original inner-code by performing PI deinterleave since all thedata except ID and IED are set as the objects of scramble.

Therefore, although the effect of PI interleave becomes a little weakwhen the information which is needed before forming an ECC block in RSVetc. at the time of reproduction is included, it is necessary to removethe data as well as ID from the objects of the interleave.

Moreover, as shown in FIG. 14, if removing ID and IED from the objectsof PI interleave, in regard to the conversion rules F_(i)(x) of theinner-code including ID and IED, it is assumed that x=1, . . . , 182 andthe values of x show position addresses as shown in FIG. 2. The functioncan be revised to so that F₁(n)=n (for n=1, 2, 3, 4, 5, and 6), or thefunction can made to limit x to be in the range of 6 to 182.

FIG. 2 on which is briefly touched above will be described again. FIG. 2is an example of a diagram having shown the method of a data list at thetime of adopting PI interleave with the conversion rule F_(i)(x) for PIinterleave to the inner-code described in FIG. 6 where the presentinvention is described above. An inner-code is 182 bytes of data train,data (A) denotes the inner-code after the addition of PI and PO, anddata (B) denotes 182 bytes of data train which is given PI interleave bythe conversion rule F_(i)(x) and is rearranged in the sequence of datathereof. Here, although the data (B) is an example of rearranging dataevery 13 pieces, the conversion rule F_(i)(x) is not limited to this,but is enough to discontinuously rearrange the data.

Two or more kinds of conversion rules F_(i)(x) are prepared in order toperform different values of PI interleave. In a DVD, the conversionrules of up to 208 kinds are prepared, and error counts on outer-codesin an ECC block are equalized as shown in FIGS. 10A to 10D by applyingthe different conversion rule for every inner-code. Hence, cases thaterror correction to outer-codes become possible increases. Thus, itbecomes possible to increase correction capacity by performing differentPI interleave to the inner-codes and recording the inner-codes on arecord medium. Moreover, this effect becomes still larger when the codeis decoded repeatedly.

Next, a method of implementing the conversion rule for this PIinterleave in a circuit will be described. First, an example of aconfiguration of a DVD recording and reproducing apparatus according tothe present invention will be described by using FIG. 15. Although arecording and reproducing apparatus is described as an example here, thepresent invention is applicable also to a reproduction dedicated deviceand a record dedicated device.

An optical pickup 1502 performs record and reproduction of data on arecord medium 1501 such as a DVD, and a spindle motor 1503 rotates adisk. Moreover, a servo 1504 controls the optical pickup 1502 or thelike. A read channel 1505 performs waveform equalization and doubling ofan analog reproductive signal read from the record medium 1501, andsynchronous clock generation. A decoder 1506 consists of a demodulationcircuit 1507 performing 8/16 demodulation of data read, and an errorcorrecting circuit (1508, 1518) performing the processing of removingerrors included in the data, and RAM 1509 a temporarily stores the dataat the time of reproduction. RAM 1509 b temporarily stores the data atthe time of record. This can be also used as the RAM 1509 a. Numeral1514 is a laser driver. A modulation circuit 1512 performs themodulation of the data at the time of record, and an encoding circuit1513 consists of an error correcting code generation circuit addingparity of error correcting code, PI and PO, and a scramble circuitperforming scramble processing. An interface 1515 controls theinput/output of data with a host system, and a microcomputer 1516generalizes the system. In addition, it is also possible to use amicrocomputer as the error correcting code generation circuit adding theerror correcting code parity PI and PO.

A PI interleave circuit (signal processing circuit which rearranges thedata in an inner-code as shown in FIG. 2) 1517 implements the presentinvention, and a PI deinterleave circuit 1518 is a signal processingcircuit which performs cancellation of PI interleave and processingshown in FIG. 13. That is, the PI interleave circuit 1517 rearranges thesequence of word bytes for the data train which consists of a pluralityof word bytes who constitutes an error correcting code, and the PIdeinterleave circuit 1518 restores the data train, which is rearranged,to the data train in the sequence before being rearranged.

The PI interleave circuit 1517 has SRAM and a register which can storeat least 182-byte data in a system where PI interleave closed within oneinner-code is performed. Hence, the PI interleave circuit 1517 readsdata every inner-code from the RAM 1509 b after ECC block generation atthe time of record, and temporarily stores the data in the sequence atthe time of being read, that is, in the form of an inner-code in theregister. After that, the PI interleave circuit 1517 writes the data onthe register again in RAM 1509 b while converting the data listaccording to predetermined PI interleave conversion rules.

The PI deinterleave circuit 1518 has SRAM and a register which can storeat least 182-byte data in a system where PI interleave closed within oneinner-code is performed. At the time of the reproduction after data isread from a DVD, the PI deinterleave circuit 1518 reads data from theRAM 1509 a every inner-code immediately after 8/16 demodulation andtemporarily stores the data in the register in the present sequence.After that, the PI deinterleave circuit 1518 writes the data on theregister again in RAM 1509 a while converting the data list according topredetermined PI interleave conversion rules. Moreover, similarprocessing can be also performed in the following configuration. Thatis, in the PI deinterleave circuit 1518, the numbers of SRAM andregisters are increased, and arranged just after the demodulationcircuit in the decoding circuit 1508, and the data outputted from thedemodulating circuit is directly inputted into the register so that thedata train having the byte count equivalent to the count of theinner-code is arranged. Then, the PI deinterleave circuit 1518 arrangesthe data, saved in the register, in the RAM 1509 a while performing PIdeinterleave of the data.

Next, a PI interleave circuit and a PI deinterleave circuit that areshown in FIG. 15 will be described. FIG. 19 shows an example of the PIinterleave circuit 1517 where PI interleave conversion rules are definedby using the M-series generating circuit 1901, which is a circuit thatgenerates the maximum periodic column; e.g., the maximum period column([=]referred to as the M-series) is 255 in the case of using an 8-bitregister (i.e., 2⁸−1). Moreover, here, it is assumed that the inner-coderead from the RAM 1509 b has been already stored in a shift register1902. As write control signals to the RAM 1509 b, there are a writerequest signal, an address (however, referred to as 1 to 182 forconvenience here) in the RAM 1509 b, and write data. When the writerequest signal is outputted, a write request acknowledge signal, whichshows that data is written, is inputted from the RAM 1509 b.

In this circuit, when the write request acknowledge signal is inputted,that is, the timing when the data is written, the shift register 1902shifts. Moreover, the M-series generating circuit 1901 also changes tothe following value if the write request acknowledge signal is inputted,or if the signal of 1 to 255 generated by the M-series generatingcircuit 1901 exceeds the address to be required, i.e., if the signal hasthe value of 183 or more. Here, the value range is not necessary to be 1to 255. In a DVD, the inner-code is 182 bytes, and PI interleave in thedata in all the inner-codes is concerned here. Hence, an output from the8-bit M-series generating circuit is used. Moreover, the write requestsignal is outputted when the address made in the M-series generatingcircuit 1901 is determined to be 182 or less by a request generationjudging circuit 1903.

This is to make an address skipped if the address made in the M-seriesgenerating circuit 1901 exceeds 183, because PI interleave processingcannot be performed.

FIG. 20 shows an example of the PI deinterleave circuit 1518 where PIinterleave conversion rules are defined by using the M-series generatingcircuit 1901. Moreover, here, it is assumed that the data train readfrom the RAM 1509 a has been already stored in a register 2001.

As write control signals to the RAM 1509 a, there are a write requestsignal, an address in the RAM 1509 a, and write data. When the writerequest signal is outputted, a write request acknowledge signal, whichshows that data is written, is inputted from the RAM 1509 a.

In this circuit, when the value of the same M-series generating circuit1901 as the M-series generating circuit 1901 where the PI interleaveconversion rules are defined exceeds 183, the following value isoutputted from the M-series generating circuit 1901. When the value is182 or less, a write request is generated, and one byte of data in thedata train chosen with the value of this M-series generating circuit1901 is written in the address which a counter 2002 shows. Moreover,since a write request acknowledge signal is inputted when writing isperformed, the counter 2002 which generates an address shows thefollowing value, and the M-series generating circuit 1901 also shows thefollowing value.

In this circuit also, it is necessary to skip an address if the addressmade in the M-series generating circuit 1901 exceeds 183, because PIdeinterleave processing cannot be performed.

Moreover, in these circuits, if an address is 1 to 6 in the requestgeneration judging circuit in the inner-code containing ID, the addressis treated similarly to a case of being 183 or more. When overwritingthe data train, which is given PI interleave, to the original inner-codeof the RAM 1509 b, i.e., the inner-code stored in the register 1902, itis not necessary to write ID and IED in the RAM 1509 b. Moreover, whenstoring the data train in another area of the RAM 1509 b, a systemwriting ID and IED in a predetermined position is added.

However, a countermeasure for the inner-code containing ID can be easilyachieved by adding an offset to an address, or the like.

Many kinds (208 or more kinds required of PI interleave conversion ruleswhich are different in all inner-codes in a DVD) of M-series defining PIinterleave rules that are used in FIGS. 19 and 20 can be generated inthe following combination.

This can be easily implemented by combining the following items 1 and 2.

1. Changing of the kind of feedback of the shift register generatingM-series (corresponding to the relation between FIGS. 16A and 16B).

2. Rearrangement of the position of data outputted from the shiftregister (corresponding to the relation between FIGS. 16A and 17A).

For example, it is assumed that the positions of the data outputted fromthe shift register in 13 inner-codes in the data unit 2 are rearrangedby changing the feedback rules of the M-series generating circuit everyunit of the data unit 2 in FIG. 1, i.e., every unit of the data unit inFIG. 14. Then, it is possible to obtain 208 kinds of different PIinterleave conversion rules.

Moreover, different M-series can be also generated by changing the valueof a certain bit as shown in FIG. 17B. However, since zero may beoutputted from M-series in this case, and a value at the time of theregister being zero and an address is not generated at the value“AA=170” in hexadecimal notation in FIG. 17B, it becomes necessary to0x170 from the obtained value to produce a suitable address. However,these can be used as M-series that define PI interleave rules. Moreover,similarly, it is clear that an address can be converted by using a logiccircuit obtained by combining OR, AND, and NOT.

As shown in FIG. 23A, values obtained by adding values different inevery row (however the same row fixed value) to the value outputted fromeach M-series generating circuit 1901 in FIGS. 16A, 16B, 17A, and 17Bthat are shown above are also M-series. Hence, the M-series can be usedas PI interleave conversion rules according to the present invention.However, in this case, a carry to the ninth bit (MSB) that is generatedby performing addition is ignored.

Moreover, values obtained by substituting a multiplier 2303, as shown inFIG. 23B, for an adder 2302 in this diagram, and multiplying the fixedvalue corresponding to each row on a finite field GF (28) are alsoM-series. Hence, the M-series can be used as PI interleave conversionrules according to the present invention. A line-counter 2301 counts theposition of the inner-code in a product code, i.e., a line address.

As a method of generating a plurality of PI interleave conversion rulesthat is for achieving the object of the present invention to performs PIinterleave, that is, for making burst errors, produced at random perseveral bytes, equally dispersed in all outer-codes, and is a simplestcircuit, there is a method of changing the initial value of the M-seriesgenerating circuit 1901 shown in FIG. 19 according to a row. This meansthat M-series generated by the same M-series generating circuits 1901are generated by shifting the M-series. As an example, there is a methodof substituting a row address as the initial value of each PI interleaveconversion rule. Thereby, at least 182 kinds of PI interleave conversionrules are generated. However, in order to use PI interleave conversionrules which are different in all 208 rows, it is necessary to combinethis method with another PI interleave conversion rule generatingmethod. In addition, as long as a method can change M-series accordingto a row, the method besides the above-described examples can be used.

It is also possible to realize the PI interleave circuit 1517 and PIdeinterleave circuit 1518, which are shown in FIG. 15, with anothermethod without using the M-series generating circuit 1901.

This is a method of realizing PI interleave conversion rules with ROM ora circuit as shown in FIGS. 18A and 18B instead of the M-seriesgenerating circuit 1901. In particular, this is effective when onlyseveral kinds of PI interleave conversion rules are necessary. Moreover,a still higher effect is expectable in that an address can be set freelysuch that PI interleave rules are managed with the distance between dataadjacent to each other in an inner-code in order to advance randomcharacteristics.

Moreover, there is a method of using arithmetic progression as a methodexcept methods using M-series as PI interleave conversion rules.

Here, since what is necessary is just to use 182 arbitrary numbers as PIinterleave rules in a DVD as PI interleave rules, suppose that numbers 0to 181 are used.

This is a method of rearranging the list of an inner-code according toarithmetic progression, for example, rearranging positions of the datain the inner-code according to PI interleave rules that is, 0, 3, 6, 9,. . . , 177, 180, 1, 4, 7, . . . , 178, 181, 2, 5, 8, . . . , 176, 179in the case of using a progression where numbers increases by 3.

In this case, it is necessary to use a constant, which is different ineach row, as an increment. Nevertheless, when numbers that are coprimeto 182 are used as constants, in regard to numbers exceeding 181, valuesobtained by subtracting 182 from the numbers can be used as theconstants. However, when numbers that are not coprime to 182 are used asconstants, for example, when the increment is 2, the numbers become 0,2, 4, 8, . . . , 180, 0, 2, 4, . . . , and hence it becomes necessary toprovide a system of adding one when exceeding 182 so that the samenumbers may not appear twice.

Moreover, if most target burst errors generated at random are 10 bytesor less, it is better to choose 11 or more as an incremental constant.

However, when 182 bytes are selected as an inner-code when an arithmeticprogression is used, it is necessary to note that the case where one isselected as a constant and the case that 181 is selected as a constantare the same in an object of dispersing errors in the differentouter-codes.

This is because adjacent numbers become the same although there isdifference between the left and the right since the list becomes 0, 1,2, 3, 4, . . . , 181 when one is selected as a constant, and the listbecomes 0, 181, 180, . . . , 4, 3, 2, 1 when 181 is selected.

An example (only numbers that are coprime to 182 except one are used) ofthe circuit that generates an arithmetic progression is shown in FIG.24.

In this diagram, an incremental constant is selected and used by beingswitched according to the value of a row address changed and is used sothat values outputted from an 8-bit register 2401 becomes an arithmeticprogression and a different series as much as possible may be obtainedaccording to an inner-code, that is, according to a row.

Moreover, FIGS. 25 and 26 show examples where arithmetic progressionsare applied to the PI interleave circuit 1517 and PI deinterleavecircuit 1518 in FIG. 15. This can be configured only by replacing theM-series generating circuit 1901 in FIGS. 19 and 20, which is describedabove, with the arithmetic progression generating circuit 2501 in FIG.24.

The circuit in FIG. 19 is cited as an example of the M-series generatingcircuit 1901 of the PI interleave circuit 1517 in FIG. 15, and themethod of arranging data in the addresses which corresponds to anM-series every one byte from a head of the data in an inner-code isshown. However, there is a method of arranging the data, stored at thepositions on the inner-code generated by the M-series, in order of theM-series by using the PI deinterleave circuit 1518 in FIG. 20 as the PIinterleave circuit 1517.

Moreover, FIG. 19 shows the PI deinterleave circuit 1518 correspondingto this.

Naturally, when a different M-series is used and this method is alsoused, the object to disperse burst errors on different outer-codes canbe attained.

However, when this method is used, burst errors cannot be dispersed ondifferent outer-codes by changing the initial value of an M-series ineach row.

The relation between two kinds of these PI interleave methods are thesame as the arithmetic progression generating circuits 2501 described byusing FIG. 25 showing the PI interleave circuit 1517 and FIG. 26 showingthe PI deinterleave circuit 1518.

PI interleave conversion rules can be configured by some combinationscontaining the M-series and arithmetic progression, which are introducedabove, as well as one method, and the circuit which realizes them can bealso realized by the combination of respective elements.

Moreover, it is also good to combine address decoders 1801 and 1802constituted by the M-series generating circuit 1901, ROM, and circuitsin order to generate many PI interleave conversion rules.

Moreover, in order to take PI interleave conversion rules intoconsideration from a circuit and to perform transform processing at highspeed, as shown in FIG. 21, it is possible to simultaneously perform aplurality of PI interleave by using the same conversion rule. It is alsopossible to simultaneously perform two or more bytes (2 bytes in FIG.22) of PI interleave within the same inner-code, as shown in FIG. 22.That is, it is possible to make two or more bytes be a group, and torearrange the order of groups by a group.

When these are actually implemented into circuits, the optimal PIinterleave method can be selected in consideration of the bus width ofRAM, and data allocation according to processing speed required. Inaddition, it is necessary to also take into consideration of the circuitscale at the time of implementation, and the degree of performanceimprovement obtained by the present invention.

Moreover, although these diagrams show examples at the time ofperforming PI interleave by 2 bytes unit, three or more are sufficientas the size of the inner-code to which the same PI interleave isactually applied.

Although cases where the present invention is applied to a DVD aredescribed through embodiments, the present invention is effective at adigital data recording and reproducing apparatus, including a productcode, and a digital data recording and reproducing method.

In addition, it should be noted that, when recording to a record mediais performed according to the list of the outer-code in a product code,the inner-code used in the explanation corresponds to the outer-code.Moreover, although the signal processing circuit using an M-series andan arithmetic progression is exemplified in the PI interleave circuit1517 and PI deinterleave circuit 1518, other pseudo-random numbergenerating circuits or the like can be used.

1. A data recording method for recording data to a recording mediumcomprising the steps of: forming a data block organized as data columnsand data rows, each data row comprising a plurality of bytes, the datablock including identification data indicative of positional informationin the data block; for each data column in the data block, adding bytesto include an error correcting code parity; rearranging the order ofbytes in each data rows according plural rearranging rules to produce arearranged data block, including rearranging a first row of dataaccording to a first rearranging rule and rearranging at least a secondrow of data according to a second rearranging rule different from thefirst rearranging rule; for each data row in the rearranged data block,adding s SYNC code; and recording the rearranged data block to arecording medium.
 2. A data reproducing method of reproducing datarecorded on a recorded medium, comprising the steps of: reproducing adata block on the recording medium; and performing an error correctionprocess on the data block reproduced, wherein the recorded mediumcomprises a plurality of data blocks, each data block organized as datacolumns and data rows, each data column including an error codecorrecting parity, each data block including positional information inthe data block, wherein for a first data row of each data block, bytescomprising the first data row are ordered in accordance with a firstrearranging rule and a SYNC code is added to the first data row, whereinfor a second data row of said each data block, bytes comprising thesecond data row are ordered in accordance with a second rearranging ruleand a SYNC code is added to the second data row.